I choose the Middle Path
It is quite plausible that Braig is significantly interlaced with Xehanort's statement. Nomura hinted that Braig's sudden change in eye color had something to do with Master Xehanort. Other than Terra, that was the only plot point alluded to Master Xehanort's enduring subsistence.
Yellow eyes are an indicator of darkness immersion, Xehanort requires a vessel teeming with darkness. Perhaps seducing Braig to darkness was a failsafe in the event his plan with Terra failed.
Briag is likely one of those roads, and maybe Isa would become one as well. There may also be more "hidden players" we've yet to even encounter. MX was intelligent, so I doubt he'd risk it all on one fusion. He might have many people who can be used as vessels.
"Mr. Slughorn, is it possible to split the soul to 7 parts" - or something like that. (that was from Harry Potter)